1. Field of the Invention
The present invention relates to a communication terminal, especially a communication terminal whose display unit having a limited display area is effectively used to improve its handiness.
2. Background Art
The communication terminal of the present invention is typically a mobile communication terminal, especially a pager (pocket bell), a PHS (personal handy phone system) phone, a cellular phone and the like. Personal computers endowed with communication capability are also included therein.
Functions which communication terminals are provided with are increasing in number to meet various user demands. On the other hand, miniaturization of some communication terminals moves forward, and therefore, the display areas of their display units are becoming smaller. Consequently, the need of realizing more functions using a smaller display area is becoming stronger.
One of the functions which a communication terminal is provided with is storage and reproduction of messages. It enables sending a message from a transmitting terminal to a receiving terminal via a switching station, and reproducing the message at the receiving terminal. The message may be a message of character codes or a voice message. In the case of a text message, the switching station transmits the message to the receiving terminal, and the message is stored in a memory unit within the receiving terminal until it is reproduced or displayed by an addressee. In the case of a voice message, the voice data itself is stored in a voice mail center within the switching station, and information indicating existence of the voice message is transmitted from the station to the receiving terminal. The voice data is transmitted in response to an addressee's requirement, and reproduced (vocalized) at the receiving terminal. There is a communication system which can transmit identifying information together with a message, the information indicating whether the message is a preferential (urgent) one or not. The communication system based on U.S. Standard TIA/EIA/IS637 is one example thereof.
There is also a communication terminal which holds a message even after the message is reproduced until it is deleted by a specific deleting operation. In such a communication terminal provided with a message displaying facility, it is desirable to provide indications to distinguish a preferential message from ordinary messages at the time of displaying them in list form. However, it is impracticable when the display area is small. Further, although it is convenient to indicate not only the number of text messages not yet reproduced but also the number of text messages already reproduced, it is also impracticable when the display area is small.
Further, the full text of a message cannot be displayed if it is long, and it has to be scrolled, which causes inconvenience in reading the message. This problem can be serious when displaying E-mail of a long text from a personal computer and the like in the display unit of a communication terminal, such as a cellular phone.
Further, there is a communication terminal which, when there arises reception error or memory overflow while it is used for voice communication, indicates information immediately on its current screen to notify a user of that status if it is urgent and, if it is not urgent, indicates the information at the time of returning to the initial screen. In such a communication terminal, if the power is turned off before returning to the initial screen, the information is not indicated and, accordingly, the user cannot receive the information until the power is turned on next.
There is also a communication terminal in which, for setting the volume of a sound, such as a received sound, transmitting sound, key click sound and the like, a setting of illuminating time of the backlight, a setting of notifying procedure of an incoming call, and for lookup in a phone directory and so on, an operation which includes selecting one of options in each selection screen (a menu screen) to open the next menu screen, is repeated in order to make desired settings by selecting necessary functions. Since the number of options that can be displayed in the display area is limited, there is known a system that enables making a selection from options other than those currently displayed in the display area by operating a ten-key pad. In such a case allowing selection of options other than those currently displayed in the display area, when a return to the previous screen has been made the option selected is not displayed, which causes inconvenience.
Furthermore, in a communication terminal of a cellular phone type in which one of an external speaker and an external microphone, and an internal speaker and an internal microphone can be selected, it is preferable to indicate the status of the selection. However, it may be impossible if the display area is small.